A key U.S. senator says the Obama administration must do more to fight currency manipulation by trading partners that puts U.S. companies at a disadvantage.

Orrin Hatch heads the Senate Finance Committee, which plays a key role in approving - or rejecting - several pending trade deals.

Hatch is apparently complaining about nations that deliberately force down the value of their currency to give their exports a price advantage on global markets.

The senator said he will address currency problems in a bill called "Trade Promotion Authority" or TPA, which he plans to introduce soon.

"It is essential that Congress know how the administration intends to address this problem in ongoing negotiations. Pretending these concerns don’t exist will not suffice. The administration must engage much more effectively with Congress on this issue if they want to receive strong support for TPA and any subsequent trade agreements," said Hatch.

TPA allows Congress to vote to reject or approve treaties that Washington has worked out with other nations, but does not allow members of Congress to amend the deals.

Hatch says hammering out a strong TPA is the way Congress can send clear instructions to the administration officials haggling with other nations. He says it should also include strong protection for intellectual property, prohibits special favors for state-owned enterprises in other nations, and offers a mechanism for investors to settle disputes with governments.

Hatch says the current U.S. trade agenda is the most ambitious in history. It includes the Trans Pacific Partnership, which is said to be nearing completion after years of haggling among 12 Pacific nations.

A proposed trade deal between the United States and the European Union, called the Transatlantic Trade and Investment Partnership is at an earlier stage of negotiation.

Previous trade deals have focused on cutting tariffs in the hope of boosting trade by making it less expensive.

But new proposals focus on "non-tariff" barriers. These include differences in national rules protecting workers, food safety, solving business disputes, and other issues.

Some proposals to change these rules are controversial because opponents say most of them were put in place by democratically-elected governments and should not be removed by what they see as an un-democratic process.

Senator Hatch, a Republican, spoke in Washington on Friday. Most Republicans and their business allies generally support trade deals. President Obama, unlike many Democrats, also supports trade agreements. But many of his usual Democratic party allies in Congress, the environmental movement, and organized labor oppose trade agreements.